Dentists are still encouraging patients to return for excessive appointments and follow-ups, putting income ahead of care, research suggests.Data gathered by the Conservatives shows dentists to be “gaming the system”.

The Tory analysis, based on figures for 2008-09, suggests that 6.8 million slots could have been made available to those without access to an NHS dentist had they not been used for excessive appointment-setting or needless splitting of courses of treatment into separate sessions.

The Tories calculate the cost to NHS patients of “unnecessary charges” at £117 million, up from £109 million the year before. The burden represents a fifth of the £572 million charged each year for treating NHS patients.

Andy Burnham, the outging Health Secretary, acknowledged last year that dentisty remained “unfinished business” after the failure of a new dentists’ contract to address problems with a so-called drill and fill culture.

An independent review ordered by the labour Government, led by Jimmy Steele, of Newcastle University, found that dentistry was too preoccupied with treatment rather than prevention, and that dentists should be paid according to the number of patients on their list and penalised for poor work that leads to repeated visits.

Professor Steele’s proposals, which were accepted by the Government and put into pilot schemes, include rewarding dentists for registering new patients and building relationships with existing ones. Income is determined by the size of the patient-list, quality of care and the number of courses of treatment.

Andrew Lansley, the Tory health spokesman, who acquired the figures from parliamentary questions in February, said that the lack of political drive to rectify problems with dentistry was shown by its absence from the manifestos of Labour and the Lib Dems.